81528217 has 2 divisors, whose sum is σ = 81528218. Its totient is φ = 81528216.

The previous prime is 81528211. The next prime is 81528229. The reversal of 81528217 is 71282518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79281216 + 2247001 = 8904^2 + 1499^2 .

It is a cyclic number.

It is not a de Polignac number, because 81528217 - 2⁷ = 81528089 is a prime.

It is not a weakly prime, because it can be changed into another prime (81528211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40764108 + 40764109.

It is an arithmetic number, because the mean of its divisors is an integer number (40764109).

Almost surely, 2^81528217 is an apocalyptic number.

It is an amenable number.

81528217 is a deficient number, since it is larger than the sum of its proper divisors (1).

81528217 is an equidigital number, since it uses as much as digits as its factorization.

81528217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8960, while the sum is 34.

The square root of 81528217 is about 9029.2977024794. The cubic root of 81528217 is about 433.6133534630.

The spelling of 81528217 in words is "eighty-one million, five hundred twenty-eight thousand, two hundred seventeen".